When you think of seizures, you may think of what used to be called a grand mal seizure (now more commonly referred to as a tonic-clonic seizure) and picture a child on the floor, jerking uncontrollably and losing consciousness. But there are other types of seizures that can occur in childhood, and some greatly resemble the kind of behaviors children with sensory integration disorder might exhibit.
A child who stares into space and can't be instantly brought to attention may be underresponsive to the sights and sounds in her environment due to sensory integration problems, or may be having an absence seizure (sometimes called a petit mal seizure). A child who is making what seem to be odd, repetitive, purposeless movements may be trying to jump-start her proprioceptive or vestibular senses, or may be having a complex partial seizure.
Overlap between these two disorders is possible. A child can have a seizure disorder and also have sensory integration disorder, or he might have one that is mistaken for the other. Either way, an increased knowledge and understanding of your child's sensory strengths and weaknesses will help sort the different behaviors out and make it clear when there are changes that might indicate seizures.
For information on childhood seizures, seek out a copy of Seizures and Epilepsy in Childhood: A Guide for Parents, by John M. Freeman, M.D., Eileen P. G. Vining, M.D., and Diana J. Pillas. It's filled with easy-to-understand information and provides confidence that your child and your family can function with this disability.